The present invention relates to cementing operations. More particularly, in certain embodiments, the present invention relates to cement compositions and methods of cementing in a subterranean formation that include sub-micron alumina for accelerating setting.
In general, well treatments include a wide variety of methods that may be performed in oil, gas, geothermal and/or water wells, such as drilling, completion and workover methods. The drilling, completion and workover methods may include, but are not limited to, drilling, fracturing, acidizing, logging, cementing, gravel packing, perforating and conformance methods. Many of these well treatments are designed to enhance and/or facilitate the recovery of desirable fluids from a subterranean well.
In cementing methods, such as well construction and remedial cementing, well cement compositions are commonly utilized. For example, in subterranean well construction, a pipe string (e.g., casing and liners) may be run into a well bore and cemented in place using a cement composition. The process of cementing the pipe string in place is commonly referred to as “primary cementing.” In a typical primary cementing method, a cement composition may be pumped into an annulus between the walls of the well bore and the exterior surface of the pipe string disposed therein. The cement composition sets in the annular space, thereby forming an annular sheath of hardened, substantially impermeable cement that supports and positions the pipe string in the well bore and bonds the exterior surface of the pipe string to the subterranean formation. Among other things, the annular sheath of set cement surrounding the pipe string functions to prevent the migration of fluids in the annulus, as well as protecting the pipe string from corrosion. Cement compositions also may be used in remedial cementing methods, such as squeeze cementing and the placement of cement plugs.
The hydration of the cement in these cementing methods is a complex process because several phases may take part in the reaction simultaneously. In order to control the reaction processes to render the compositions suitable for well cementing, various additives such as retarders, strength enhancers, and accelerators may be added. However, the operating conditions for wells are becoming more challenging and demanding, and the search for new materials continues to meet these challenges. For instance, cement slurries used in well cementing often encounter problems of gaining sufficient strength in a reasonable amount of time for well operations to continue. The costs associated with wait-on-cement (“WOC”) play an important role in well cementing. This problem may be further aggravated if latex is used with the cement. Furthermore, when latex is present in cement slurries, addition of calcium salts or other salts to accelerate the setting of cement, for example, at low temperatures, can cause coagulation of the latex with resultant gelling of the cement slurries. This gelling may result in premature loss of fluidity of the cement slurry before placement in the desired location in the well bore. Latex may be used for fluid loss control, to provide resiliency to the set cement, and/or to reduce the issues associated with gas channeling. Latex-containing cement compositions, however, may have slower strength development with respect to comparable cement compositions.